U.S. patent application number 12/690387 was filed with the patent office on 2011-03-17 for apparatus and method for enhancing connectability in led array using metal traces.
This patent application is currently assigned to Bridgelux, Inc.. Invention is credited to Shane Harrah, Rene Peter Helbing, Michael Solomensky.
Application Number | 20110062482 12/690387 |
Document ID | / |
Family ID | 43729627 |
Filed Date | 2011-03-17 |
United States Patent
Application |
20110062482 |
Kind Code |
A1 |
Solomensky; Michael ; et
al. |
March 17, 2011 |
Apparatus And Method For Enhancing Connectability In LED Array
Using Metal Traces
Abstract
A light-emitting device having multiple light-emitting diode
("LED") dice organized in an array capable of configuring LED dice
in series, parallel, and/or a combination of series and parallel
via metal traces is disclosed. In one aspect, the light-emitting
device includes a substrate, a dielectric layer, an LED array, and
a metal trace. The dielectric layer, which is disposed over the
substrate, provides electric insulation. The LED array capable of
generating light is able to enhance flexibility of LED connections
using a metal trace. The metal trace has a predefined shape
configured to travel through the LED array for facilitating
electric connections.
Inventors: |
Solomensky; Michael;
(Sunnyvale, CA) ; Harrah; Shane; (Sunnyvale,
CA) ; Helbing; Rene Peter; (Sunnyvale, CA) |
Assignee: |
Bridgelux, Inc.
Sunnyvale
CA
|
Family ID: |
43729627 |
Appl. No.: |
12/690387 |
Filed: |
January 20, 2010 |
Current U.S.
Class: |
257/99 ;
257/E21.499; 257/E33.066; 438/28 |
Current CPC
Class: |
H01L 33/38 20130101;
H01L 2224/49113 20130101; H01L 33/62 20130101; H01L 2924/09701
20130101; H01L 2224/48137 20130101; H01L 25/0753 20130101 |
Class at
Publication: |
257/99 ; 438/28;
257/E33.066; 257/E21.499 |
International
Class: |
H01L 33/00 20100101
H01L033/00; H01L 21/50 20060101 H01L021/50 |
Claims
1. A light-emitting device, comprising: a dielectric layer disposed
over a substrate and configured to provide electric insulation; a
light emitting diode ("LED") array having a plurality of LED dice
disposed over the substrate for generating light; and a metal trace
disposed over the dielectric layer and configured to provide
electric connections, wherein the metal trace has a predefined
shape configured to travel through the LED array.
2. The device of claim 1, further comprising a metal layer disposed
over the dielectric layer and configured to conduct electrical
power.
3. The device of claim 1, wherein the metal trace facilitates LED
dice configurations utilizing bond wires.
4. The device of claim 2, wherein the metal trace is capable of
configuring at least a portion of the LED dice in a series
configuration.
5. The device of claim 2, wherein the metal trace is capable of
configuring at least a portion of the LED dice in a parallel
connection.
6. The device of claim 2, wherein the metal trace is capable of
facilitating a combination of a series configuration of the LED
dice and a parallel configuration of the LED dice.
7. The device of claim 6, wherein the metal trace is an S-shaped
electrical conductive plate.
8. The device of claim 1, wherein the metal trace is a Z-shaped
electrical conductive plate.
9. The device of claim 1, wherein the metal trace is a straight
electrical conductive strip.
10. A method of fabricating a light emitting device, comprising:
depositing a dielectric layer over a base layer to provide electric
insulation; overlaying a metal trace having a predefined shape on
the dielectric layer to provide electrical connections; and
depositing a plurality of light emitting diode ("LED") dice in an
array formation over the base layer, wherein depositing the
plurality of LED dice includes disposing LED dice in such a way
that allows the metal trace to travel through the array
formation.
11. The method of claim 10, further comprising depositing an
electric conductive metal layer over the dielectric layer for
providing electrical power.
12. The method of claim 11, wherein overlaying a metal trace having
a predefined shape on the dielectric layer further includes
disposing an S-shaped metal plate over the dielectric layer.
13. The method of claim 11, wherein overlaying a metal trace having
a predefined shape on the dielectric layer further includes
disposing a Z-shaped metal plate over the dielectric layer for
facilitating one or more bond wire connections.
14. The method of claim 11, wherein overlaying a metal trace having
a predefined shape on the dielectric layer further includes
disposed a straight metal strip over the dielectric layer to
facilitate one or more bond wire connections.
15. The method of claim 10, further comprising configuring at least
a portion of the plurality of LED dice in a series configuration
utilizing bond wires and the metal trace.
16. The method of claim 10, further comprising configuring at least
a portion of the plurality of LED dice in a parallel connection
utilizing bond wires and the metal trace.
17. The method of claim 10, further comprising configuring at least
a portion of the plurality of LED dice in a combination of series
connections and parallel connections via utilization of bond wires
and the metal trace.
18. A light emitting diode ("LED") lamp, comprising: a package; and
an LED apparatus coupled to the package and including: a dielectric
layer disposed over a substrate and configured to provide electric
insulation; a light emitting diode ("LED") array having a plurality
of LED dice disposed over the substrate for generating light; and a
metal trace disposed over the dielectric layer and configured to
provide electric connections, wherein the metal trace has a
predefined shape configured to travel through the LED array.
19. The lamp of claim 18, wherein the LED apparatus further
including a metal layer disposed over the dielectric layer and
configured to conduct electrical power.
20. The lamp of claim 19, wherein the metal trace is able to
configure the LED dice in one or more connecting configurations
utilizing bond wires.
21-25. (canceled)
Description
FIELD
[0001] The exemplary aspect(s) of the present invention relates to
lighting devices. More specifically, the aspect(s) of the present
invention relates to light-emitting semiconductor fabrication with
flexible LED connections capable of reconfiguring electrical
connections of light emitting diodes ("LED") dice.
BACKGROUND
[0002] Solid-state light-emitting devices such as LEDs are
attractive candidates for replacing conventional light sources such
as incandescent and fluorescent lamps. LEDs typically have higher
light conversion efficiencies than incandescent lamps, and have
longer lifetime than conventional light sources. Certain types of
LEDs, for instance, have higher light conversion efficiencies than
fluorescent light sources and even higher conversion efficiencies
have been demonstrated in the laboratory. For LEDs to be accepted
in various lighting applications, it is important to optimize every
step of the processing and achieve the highest efficiencies
possible.
[0003] A physical characteristic associated with a conventional LED
lighting system having multiple LED dice is performance variation
in connection to the source of power supply. For example, LED dice
connected in series tend to produce more flux for a fixed amount of
current than the LED dice connected in parallel. As such, LED dice
connected in series performs well for a fixed amount of current
source with high voltage. Conversely, LED dice connected in
parallel configuration tend to provide more flux with a power
source that provides high current and low voltage than a power
source with low current and high voltage. Accordingly, the
performance of an LED lighting system can vary depending on the
availability of the power source.
[0004] A problem associated with manufacturing a conventional LED
light system is the lack of flexibility in LED connections after
substrates are fabricated. In other words, changing the LED dice
electrical connection after the substrates are fabricated is
typically difficult. Due to the tight layout of a conventional LED
light system, the flexibility of connecting LED dice in series
and/or parallel is limited after the components are formed.
SUMMARY
[0005] A light-emitting device having multiple LED dice organized
in an array capable of flexibly configuring LED dice in series,
parallel, and/or a combination of series and parallel via metal
traces is disclosed. In one aspect, the light-emitting device
includes a substrate, a dielectric layer, an LED array, and a set
of metal traces. The dielectric layer, which is disposed over the
substrate, provides electric insulation. The LED array capable of
generating light is able to enhance flexibility of LED connections
using one or more metal traces. The metal trace has a predefined
shape configured to travel through the LED array for facilitating
electric connections in multiple electrical configurations.
[0006] It is understood that other aspects of the present invention
will become readily apparent to those skilled in the art from the
following detailed description, wherein it is shown and described
only exemplary configurations of an LED by way of illustration. As
will be realized, the present invention includes other and
different aspects and its several details are able to be modified
in various other respects, all without departing from the spirit
and scope of the present invention. Accordingly, the drawings and
the detailed description are to be regarded as illustrative in
nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The exemplary aspect(s) of the present invention will be
understood more fully from the detailed description given below and
from the accompanying drawings of various aspects of the invention,
which, however, should not be taken to limit the invention to the
specific aspects, but are for explanation and understanding
only.
[0008] FIG. 1 is a diagram illustrating a lighting system having
multiple LED dice with reconfigurable connections in accordance
with an aspect of the present invention;
[0009] FIG. 2 is a diagram illustrating a lighting system having
three LED dice capable of providing reconfigurable connections in
accordance with an aspect of the present invention;
[0010] FIG. 3 is a diagram illustrating a lighting system having
three LED dice connected in series via a metal trace in accordance
with an aspect of the present invention;
[0011] FIG. 4 is a diagram illustrating a lighting system having
four LED dice connected in series via a Z-shaped metal trace in
accordance with an aspect of the present invention;
[0012] FIG. 5 is a diagram illustrating a lighting system having
multiple LED dice connected in series using a straight metal trace
in accordance with an aspect of the present invention;
[0013] FIGS. 6A-B are diagrams showing alternative metal trace
shapes used in LED array in accordance with an aspect of the
present invention;
[0014] FIGS. 7A-C illustrate images showing LED lighting devices
capable of reconfiguring LED connections using metal traces in
accordance with an aspect of the present invention;
[0015] FIG. 8A illustrates an exploded view of a lighting system
having an LED array using metal trace for flexible LED connections
in accordance with an aspect of the present invention;
[0016] FIG. 8B illustrates images of a lighting system having an
LED array using metal trace for facilitating flexible LED
connections in accordance with an aspect of the present
invention;
[0017] FIG. 9 is a flowchart illustrating a process of fabricating
a lighting device having multiple LED dice and a metal trace for
reconfigurable connections in accordance with an aspect of the
present invention;
[0018] FIG. 10 is a conceptual cross-sectional view illustrating an
exemplary fabrication process of an LED or LED devices;
[0019] FIG. 11 is a conceptual cross-sectional view illustrating an
example of an LED with a phosphor layer;
[0020] FIG. 12A is a conceptual top view illustrating an example of
an LED array that can be used with flexible LED connections in
accordance with an aspect of the present invention;
[0021] FIG. 12B is a conceptual cross-sectional view of the LED
array of FIG. 12A;
[0022] FIG. 13A is a conceptual top view illustrating an example of
an alternative configuration of an LED array that can be used with
flexible LED connections in accordance with an aspect of the
present invention;
[0023] FIG. 13B is a conceptual cross-sectional view of the LED
array of FIG. 13A; and
[0024] FIG. 14 shows exemplary lighting devices including LED
devices using flexible LED connections in accordance with an aspect
of the present invention.
DETAILED DESCRIPTION
[0025] Aspects of the present invention is described herein in the
context of a method, device, and apparatus of reconfiguring
connections of light emitting diode ("LED") dice organized in an
array using one or more metal traces.
[0026] The present invention is described more fully hereinafter
with reference to the accompanying drawings, in which various
aspects of the present invention are shown. This invention,
however, may be embodied in many different forms and should not be
construed as limited to the various aspects of the present
invention presented throughout this disclosure. Rather, these
aspects are provided so that this disclosure will be thorough and
complete, and will fully convey the scope of the present invention
to those skilled in the art. The various aspects of the present
invention illustrated in the drawings may not be drawn to scale.
Rather, the dimensions of the various features may be expanded or
reduced for clarity. In addition, some of the drawings may be
simplified for clarity. Thus, the drawings may not depict all of
the components of a given apparatus (e.g., device) or method.
[0027] Various aspects of the present invention will be described
herein with reference to drawings that are schematic illustrations
of idealized configurations of the present invention. As such,
variations from the shapes of the illustrations as a result, for
example, manufacturing techniques and/or tolerances, are to be
expected. Thus, the various aspects of the present invention
presented throughout this disclosure should not be construed as
limited to the particular shapes of elements (e.g., regions,
layers, sections, substrates, etc.) illustrated and described
herein but are to include deviations in shapes that result, for
example, from manufacturing. By way of example, an element
illustrated or described as a rectangle may have rounded or curved
features and/or a gradient concentration at its edges rather than a
discrete change from one element to another. Thus, the elements
illustrated in the drawings are schematic in nature and their
shapes are not intended to illustrate the precise shape of an
element and are not intended to limit the scope of the present
invention.
[0028] It will be understood that when an element such as a region,
layer, section, substrate, or the like, is referred to as being
"on" another element, it can be directly on the other element or
intervening elements may also be present. In contrast, when an
element is referred to as being "directly on" another element,
there are no intervening elements present. It will be further
understood that when an element is referred to as being "formed" on
another element, it can be grown, deposited, etched, attached,
connected, coupled, or otherwise prepared or fabricated on the
other element or an intervening element.
[0029] Furthermore, relative terms, such as "lower" or "bottom" and
"upper" or "top," may be used herein to describe one element's
relationship to another element as illustrated in the drawings. It
will be understood that relative terms are intended to encompass
different orientations of an apparatus in addition to the
orientation depicted in the drawings. By way of example, if an
apparatus in the drawings is turned over, elements described as
being on the "lower" side of other elements would then be oriented
on the "upper" side of the other elements. The term "lower", can
therefore, encompass both an orientation of "lower" and "upper,"
depending of the particular orientation of the apparatus.
Similarly, if an apparatus in the drawing is turned over, elements
described as "below" or "beneath" other elements would then be
oriented "above" the other elements. The terms "below" or "beneath"
can, therefore, encompass both an orientation of above and
below.
[0030] Unless otherwise defined, all terms (including technical and
scientific terms) used herein have the same meaning as commonly
understood by one of ordinary skill in the art to which this
invention belongs. It will be further understood that terms, such
as those defined in commonly used dictionaries, should be
interpreted as having a meaning that is consistent with their
meaning in the context of the relevant art and this disclosure.
[0031] As used herein, the singular forms "a", "an" and "the" are
intended to include the plural forms as well, unless the context
clearly indicates otherwise. It will be further understood that the
terms "comprises" and/or "comprising," when used in this
specification, specify the presence of stated features, integers,
steps, operations, elements, and/or components, but do not preclude
the presence or addition of one or more other features, integers,
steps, operations, elements, components, and/or groups thereof. The
term "and/or" includes any and all combinations of one or more of
the associated listed items
[0032] Various aspects of an LED luminaire will be presented.
However, as those skilled in the art will readily appreciate, these
aspects may be extended to aspects of LED luminaries without
departing from the invention. The LED luminaire may be configured
as a direct replacement for conventional luminaries, including, by
way of example, recessed lights, surface-mounted lights, pendant
lights, sconces, cove lights, track lighting, under-cabinet lights,
landscape or outdoor lights, flood lights, search lights, street
lights, strobe lights, bay lights, strip lights, industrial lights,
emergency lights, balanced arm lamps, accent lights, background
lights, and other light fixtures.
[0033] As used herein, the term "light fixture" shall mean the
outer shell or housing of a luminaire. The term "luminaire" shall
mean a light fixture complete with a light source and other
components (e.g., a fan for cooling the light source, a reflector
for directing the light, etc.), if required. The term "LED
luminaire" shall mean a luminaire with a light source comprising
one or more LEDs. LEDs are well known in the art, and therefore,
will only briefly be discussed to provide a complete description of
the invention.
[0034] It is further understood that the aspect of the present
invention may contain integrated circuits that are readily
manufacturable using conventional semiconductor technologies, such
as CMOS ("complementary metal-oxide semiconductor") technology, or
other semiconductor manufacturing processes. In addition, the
aspect of the present invention may be implemented with other
manufacturing processes for making optical as well as electrical
devices. Reference will now be made in detail to implementations of
the exemplary aspect(s) as illustrated in the accompanying
drawings. The same reference indicators will be used throughout the
drawings and the following detailed description to refer to the
same or like parts.
[0035] An LED lamp includes multiple LED dice organized in an array
which is capable of configuring LED dice in series, parallel,
and/or a combination of series and parallel via one or more metal
traces. In one aspect, the LED lamp includes a substrate, a
dielectric layer, an LED array, and a metal trace. The dielectric
layer, which is disposed over at least a portion of the substrate,
provides electric insulation. The LED array capable of generating
light is able to enhance flexibility of LED connections using one
or more metal traces. The metal trace has a predefined shape
configured to travel through the LED array to facilitate electric
connections.
[0036] FIG. 1 is a diagram 100 illustrating a lighting system
having multiple LED dice with reconfigurable connections in
accordance with an aspect of the present invention. Diagram 100
includes an LED array, a substrate 108, a patterned dielectric
layer 106, and a metal trace 118, wherein the LED array includes
LED dice 110-116. LED dice 110-116 are coupled to terminals or pads
102-104 using bond wires 120-130. It should be noted that the
underlying concept of the exemplary aspect(s) of the present
invention would not change if one or more elements (or devices)
were added to or removed from diagram 100.
[0037] The LED array, in one aspect, includes four (4) LED dice
110-116, wherein each LED die is a semiconductor diode capable of
converting electrical energy to optical light. Note that the
conversion of electrical energy to optical energy is also known as
electroluminescence. The color of the light is generally based on
the energy gap of the semiconductor used. The LED array is able to
configure layout of LED dice 110-116 such as parallel or serial
connections after the components are fabricated. Each LED die
includes a first electrical contact and a second electrical contact
capable of electrically coupling to conductive traces and/or pads.
LED dice 110-116 are disposed or fastened over substrate 108.
[0038] Substrate 108 can be a metal substrate or dielectric
substrate. The metal substrate, which is a conductive substrate,
can be made of aluminum, nickel, copper, metal alloy, and/or a
combination of electrical conductive materials. Alternatively, a
dielectric substrate, which is a non-conductive substrate, can be
made of non-conductive materials, such as ceramic, plastic, glass,
and/or materials for making printed circuit board ("PCB"). As such,
depending on applications, substrate 108 can be either made of
conductive, non-conductive, or a combination of metal and
dielectric materials.
[0039] Substrate 108, also known as reconfigurable LED array
substrate, is formed with trenches that separate and define
sections which house one or more electronic components such as LED
dice 110-116. Trenches or traces provide wiring mechanism to
facilitate electrical interconnections between individual
components. In one example, substrate 108 further includes an
integral reflector(s) shaped in a form of cavity (or cavities) to
house LED die(s). Reflector cavity walls, for instance, can be
optionally plated with reflective materials and/or filled with
molding materials used for lens and/or encapsulant. In one aspect,
substrate 108 is made of aluminum-aluminum oxide through applicable
semiconductor manufacturing technologies such as Aluminum Oxide
("ALOX") process. Depending on processing technologies, a metal
substrate can satisfy manufacturing requirements as well as
electrical interconnections, thermal limitations, and desirable
mechanical properties. Dielectric layer 106, in one aspect, is
disposed over metal substrate 108 to provide electric insulation.
Multiple electrically conductive traces such as metal trace 118 can
be subsequently disposed over dielectric layer 106. In one
instance, dielectric layer 106 includes ALOX.
[0040] Metal trace 118, in one aspect, is made of electrically
conductive materials, such as aluminum, copper, nickel, gold, or a
combination of aluminum, copper, nickel, and gold, to facilitate
movement of electrical current. Metal trace 118 is an S-shaped
metal strip configured to travel through the LED array to enhance
electric connectivity. For example, metal trace 118 passes through
LED dice 110-116 in an LED array, as illustrated in FIG. 1, to
enhance flexibility of electric connectivity. A function of metal
trace 118 is to provide additional wire bond connection(s) thereby
LED dice 110-116 can be flexibly reconfigured in a parallel
connection, series connection, or a combination of series and
parallel connections after the components are fabricated.
[0041] Referring back to FIG. 1, a first terminal of LED die 110 is
connected to a first terminal of power source 102 via bond wire 124
and a second terminal of LED die 110 is connected to a first
terminal of LED die 112 via bond wire 122. A second terminal of LED
die 112 is connected to a second terminal of power source 104.
While a second terminal of LED die 114 is connected to second
terminal 104 via bond wire 126, a first terminal of LED die 114 is
connected to a second terminal of LED die 116 via bond wire 128. A
first terminal of LED die 116 is connected to the first terminal of
power source 102 via bond wire 130. Note that the first terminal of
power source 102 can be positive potential of a power supply and
the second terminal of power source 104 can be negative potential
of a power supply. The LED array has two (2) serial strings of LED
dice wherein each string includes two LED dice. For example, LED
dice 110-112 form the first series of LED dice while LED dice
114-116 form the second series connection of LED dice. The first
series of LED dice 110-112 is in parallel with the second series of
LED dice 114-116.
[0042] An advantage of having a metal trace(s) such as metal trace
118 is to provide different number of LED dice to generate a
different combination of series and/or parallel connections
depending on the specific customer's requirements. Note that the
S-shaped metal trace 118 is for illustrated purposes, the
underlying concept of the exemplary aspect(s) of the present
invention would not change if metal trace 118 is in an H-shape,
Z-shape, I-shape, and/or any other shapes or formations.
[0043] It should be noted that a metal trace disposed over a
substrate can provide different LED interconnection patterns or
layout. In addition, it is also advantageous to have a substrate
having direct metal connection with low thermal resistance path
between a die and a bottom surface of the substrate.
[0044] FIG. 2 is a diagram 200 illustrating a lighting system
having three LED dice capable of providing reconfigurable
connections in accordance with an aspect of the present invention.
Diagram 200 includes an LED array, a substrate 108, a dielectric
layer 106, and a metal trace 118. LED dice 110-114 are coupled to
terminals or pads 102-104 using bond wires 220-230. It should be
noted that the underlying concept of the exemplary aspect(s) of the
present invention would not change if one or more elements (or
devices) were added to or removed from system 200.
[0045] The LED array includes three (3) LED dice 110-114, wherein
LED dice 110-114 are connected in three-way parallel connections
using metal trace 118. Referring back to FIG. 2, a first terminal
of LED die 110 is connected to a first terminal of power source 102
via bond wire 230 and a second terminal of LED die 110 is connected
to metal trace 118 via bond wire 222. A first terminal of LED die
112 is connected to the first terminal of power source 102 via bond
wire 224 and a second terminal of LED die 112 is connected to a
second terminal of power source 104 via bond wire 220. While a
second terminal of LED die 114 is connected to metal trace 118 via
bond wire 226, a first terminal of LED die 114 is connected to the
first terminal of power source 102 via bond wire 228. Metal trace
118 is coupled with the second terminal of power source 104 via
bond wire 232. Note that the first terminal of power source 102 can
be the positive potential of a power supply and the second terminal
of power source 104 can be negative potential of a power supply.
Diagram 200 illustrates LED dice in the LED array is configured in
three (3) strings in parallel wherein each string contains one LED
die.
[0046] An advantage of using a metal trace is to permit
reconfiguration of connectivity of LED dice in accordance with the
customer's specifications while the components such as substrates
and metal trace(s) are pre-fabricated.
[0047] FIG. 3 is a diagram 300 illustrating a lighting system
having three (3) LED dice connected in series via a metal trace in
accordance with an aspect of the present invention. Diagram 300
includes an LED array, a substrate 108, a patterned dielectric
layer 106, and a metal trace 118. LED dice 110-114 coupled to
terminals or pads 102-104 using bond wires 320-330. The LED array
includes three (3) LED dice 110-114, wherein LED dice 110-114 are
connected in series using metal trace 118.
[0048] Referring back to FIG. 3, a first terminal of LED die 110 is
connected to a first terminal of power source 102 via bond wire 330
and a second terminal of LED die 110 is connected to a first
terminal of LED die 114 via bond wire 328. A second terminal of LED
die 114 is connected to metal trace 118 via bond wire 326. A first
terminal of LED die 112 is connected to metal trace 118 via bond
wire 322 and a second terminal of LED die 112 is connected to a
second terminal of power source 104 via bond wire 320. Note that
the first terminal of power source 102 can be the positive
potential of a power supply and the second terminal of power source
104 can be negative potential of a power supply. Diagram 300
illustrates the LED array containing one (1) string of LED dice
connected in series.
[0049] FIG. 4 is a diagram 400 illustrating a lighting system
having four (4) LED dice 110-116 connected in series via a Z-shaped
metal trace in accordance with an aspect of the present invention.
Diagram 400 includes an LED array, a substrate 408, and a metal
trace 418 wherein metal trace 418 is in a Z shape. LED dice 110-114
are coupled to terminals or pads 102-104 using bond wires 420-430.
The LED array includes four (4) LED dice 110-116, wherein LED dice
110-116 are connected in series connection using metal trace
418.
[0050] Referring back to FIG. 4, a first terminal of LED die 110 is
connected to metal trace 418 via bond wire 424 and a second
terminal of LED die 110 is connected to a first terminal of LED die
116 via bond wire 430. While a second terminal of LED die 116 is
connected to a first terminal of power source 104 via bond wire
428, a second terminal of LED die 114 is connected to metal trace
418 via bond wire 426. A first terminal of LED 114 is connected to
a second terminal of LED die 112 via bond wire 422, and a first
terminal of LED die 112 is connected to a second terminal of power
source 102 via bond wire 420. Note that the first terminal of power
source 102 can be the positive potential of a power supply and the
second terminal of power source 104 can be negative potential of a
power supply. Diagram 400 illustrates an LED array containing one
(1) LED string of four (4) LED dice 110-116 connected in series
using a Z-shaped metal trace.
[0051] In one aspect, adjacent dice in each row of a matrix or
array are directly connected by bond wires between n pad(s) of one
die and p pad(s) of adjacent die in series. Dice between different
rows are electrically connected in series with bond wire(s) to a
conductive metal trace disposed over a substrate. In an alternative
aspect, adjacent dice in each column of a matrix or array are
directly connected by bond wires between n pad(s) of one die and p
pad(s) of adjacent die in series. The dice between different
columns are electrically connected in series by bond wire(s) via a
conductive metal trace situated over the substrate. It should be
noted that an independent conductive metal trace situated between
each row and column of LED dice organized in array can provide
reconfiguring LED die connections such as in series, parallel,
and/or a combination of series and parallel.
[0052] An advantage of using a Z-shaped metal trace is to provide
connection pad as well as render shorter bond wires to achieve
reconfigurable interconnections. Note that LED dice connected in
series produce more flux for a fixed total drive current than the
same number of LED dice in parallel or in series/parallel strings.
It is particularly advantageous since power supplies with high
current and low voltage are more expensive than those with lower
current and high voltage.
[0053] FIG. 5 is a diagram 550 illustrating a lighting system
having multiple LED dice connected in series using a straight metal
trace in accordance with an aspect of the present invention.
Diagram 550 includes an LED array, a substrate 408, and a metal
trace 518 wherein metal trace 518 is formed in an I shape or a
straight line. LED dice 110-116 are coupled to terminals or pads
102-104 using bond wires 520-530. The LED array includes four (4)
LED dice 110-116, wherein LED dice 110-116 are connected in series
using metal trace 518.
[0054] Referring back to FIG. 5, a first terminal of LED die 110 is
connected to metal trace 518 via bond wire 524 and a second
terminal of LED die 110 is connected to a first terminal of LED die
116 via bond wire 530. While a second terminal of LED die 116 is
connected to a first terminal of power source 104 via bond wire
528, a second terminal of LED die 114 is connected to metal trace
518 via bond wire 526. A first terminal of LED 114 is connected to
a second terminal of LED die 112 via bond wire 522, and a first
terminal of LED die 112 is connected to a second terminal of power
source 102 via bond wire 520. Diagram 550 illustrates an LED array
containing one (1) string of LED dice 110-116 using an I-shaped
metal trace.
[0055] The first terminal of power source 104, in one aspect, is a
substrate metallization that is connected to a positive (+)
terminal of LED array. The second terminal of power source 102, on
the other hand, is a substrate metallization that is connected to a
negative (-) terminal of LED array. The perimeter of cavity 540 may
be filled with silicone and/or phosphor encapsulation. An advantage
of using an I-shaped metal trace is to provide flexible connecting
pad for bond wires to achieve reconfigurable connections.
[0056] FIG. 6A is a diagram 650 illustrating an alternative metal
trace configurations used in an LED light in accordance with an
aspect of the present invention. Diagram 650 includes an LED array,
an H-shaped metal trace 680, and electrical terminals 682-684,
wherein electrical terminals 682-684 are connected to positive and
negative power supply. The LED array, in one aspect, includes nine
(9) LED dice 660-676 capable of converting electrical energy to
optical light. H-shaped metal trace 680, in one aspect, is used for
connecting pads for bond wires to provide flexible reconfigurations
in connectivity.
[0057] FIG. 6B is a diagram 690 illustrating an alternative
exemplary connection reconfiguration of an LED lighting device
having metal traces situated every other column within an LED array
in accordance with an aspect of the present invention. Diagram 690
includes an LED array and I-shaped metal traces 692 wherein the LED
array includes x rows by y columns ("X.times.Y") of LED dice.
I-shaped metal traces 692 are used to facilitate flexible
connectivity to generate different LED dice connecting
configurations in accordance with one or more specifications.
[0058] FIG. 7A illustrates images showing two LED lighting devices
capable of reconfiguring connections using metal traces in
accordance with an aspect of the present invention. Image 750 shows
an LED lighting device including an LED array and an S-shaped metal
trace 760, wherein the LED array further includes four (4) LED dice
752-758. In one aspect, the LED lighting device illustrated in
image 750 has similar configuration as the device illustrated in
FIG. 1. The lighting device uses metal trace 760 to form two (2)
strings of LED dice in parallel wherein each string includes two
LED dice.
[0059] Image 770 shows an LED lighting device including an LED
array and an S-shaped metal trace 780, wherein the LED array
further includes three (3) LED dice 772-776. In one aspect,
lighting device illustrated in image 770 has similar configuration
as the device illustrated in FIG. 2. The lighting device uses metal
trace 780 to form three (3) strings of LED dice in parallel wherein
each string includes one (1) LED die.
[0060] FIG. 7B illustrates images showing two LED lighting devices
capable of reconfiguring alternative connections using metal traces
in accordance with an aspect of the present invention. Image 786
shows an LED lighting device including an array of four LED dice
configured in four (4) strings of LED dice in parallel wherein each
string includes one LED die. Image 788 shows an LED lighting device
including an array of four LED dice configured in one (1) string of
four (4) LED dice connected in series.
[0061] FIG. 7C illustrates images showing two LED lighting devices
capable of reconfiguring alternative connections using metal traces
in accordance with an aspect of the present invention. Image 790
shows an LED lighting device including an array of four (4) LED
dice configured in one (1) string of four (4) LED dice connected in
series using an L shaped metal trace 792. Image 796 shows an LED
lighting device including an array of three (3) LED dice configured
in one (1) string of three (3) LED dice connected in series.
[0062] FIG. 8A is a diagram 850 illustrating an exploded view of a
lighting system having an LED array using a metal trace for
providing flexible LED connections in accordance with an aspect of
the present invention. Diagram 850 includes a substrate or base
layer 862, a patterned dielectric layer 860, a metal layer 858, a
metal trace 864, a solder mask layer 856, a disk 854 including
encapsulant, and a cavity ring 852. Metal layer 858 further
includes a first terminal 864 and a second terminal 866 wherein
metal layer 858 is a conductive layer, which can be made of copper,
nickel, aluminum, gold or a combination of conductive alloy. First
and second terminals 864-866 are configured to connect to negative
and positive power terminals 868-870, respectively. It should be
noted that the components illustrated in diagram 850 can be
pre-fabricated, and the connecting configuration in the LED array
can be subsequently configured according to the specification using
bond wires. Note that the underlying concept of the exemplary
aspect(s) of the present invention would not change if one or more
components (or layers) were added to or removed from diagram
850.
[0063] FIG. 8B illustrates images of LED lighting assembly having
an LED array and metal trace for facilitating flexible LED
connections in accordance with an aspect of the present invention.
Image 870 shows a top view of an LED lighting assembly having an
LED array and a metal trace 882, wherein the LED array includes
four (4) LED dice 874-880. Image 890 illustrates an isometric view
of the LED lighting assembly shown in image 870. In one aspect, the
connection configuration of LED dice 874-880 can be adjusted or
reconfigured using bond wires via metal trace 882.
[0064] The exemplary aspect of the present invention includes
various processing steps, which will be described below. The steps
of the aspect may be embodied in machine or computer executable
instructions. The instructions can be used to cause a general
purpose or special purpose system, which is programmed with the
instructions, to perform the steps of the exemplary aspect of the
present invention. Alternatively, the steps of the exemplary aspect
of the present invention may be performed by specific hardware
components that contain hard-wired logic for performing the steps,
or by any combination of programmed computer components and custom
hardware components.
[0065] FIG. 9 is a flowchart 950 illustrating a process of
fabricating a lighting device having multiple LED dice and a metal
trace for reconfigurable connections in accordance with an aspect
of the present invention. At block 952, a process of fabricating an
LED system deposits a dielectric layer over a base layer to provide
electric insulation. The base layer is a substrate that can be made
of electric conductive material or dielectric material.
[0066] At block 954, a metal trace having a predefined shape is
overlaid on the dielectric layer to provide electrical connections.
In one aspect, the process is capable of disposing an S-shaped
metal plate over the dielectric layer. In another aspect, the
process is able to dispose a Z-shaped metal plate over the
dielectric layer for facilitating one or more bond wire
connections. In yet another aspect, the process disposes a straight
metal strip over the dielectric layer to facilitate one or more
bond wire connections.
[0067] At block 956, a process deposits multiple LED dice in an
array formation over a base layer. In one aspect, the array
formation includes four (4) LED dice. In an alternative aspect, the
array formation includes three (3) LED dice.
[0068] At block 958, the process deposits LED dice in an array
formation over the base layer, wherein the depositing process is
able to dispose LED dice in such a way that allows the metal trace
to travel through the array of LED dice. In one aspect, upon
depositing an electric conductive metal layer over the dielectric
layer for providing electrical power, the process connects at least
a portion of the LED dice in series configurations utilizing bond
wires and the metal trace. While at least a portion of the LED dice
is connected in parallel connections utilizing bond wires and the
metal trace, the process is capable of configuring at least a
portion of the LED dice in a combination of series connections and
parallel connections via utilization of bond wires and the metal
trace.
[0069] At block 960, the process, in one embodiment, encloses the
LED device with incapsulant and a cavity ring. Encapsulant can be a
type of adhesive or non-adhesive material capable of sealing a
component or components. Deposing a disk together with a cavity
ring, in one example, can be the final processing stage for
fabricating the LED device.
[0070] Having briefly described aspects of lighting assemblies
capable of reconfiguring connections of LED dice using a metal
trace in which the present invention operates, the following
figures illustrate exemplary process and/or method to fabricate and
package LED dies, chips, device, and/or fixtures.
[0071] FIG. 10 is a conceptual cross-sectional view illustrating an
exemplary fabrication process of an LED or LED devices. An LED is a
semiconductor material impregnated, or doped, with impurities.
These impurities add "electrons" or "holes" to the semiconductor,
which can move in the material relatively freely. Depending on the
kind of impurity, a doped region of the semiconductor can have
predominantly electrons or holes, and is referred respectively as
n-type or p-type semiconductor regions. Referring to FIG. 10, the
LED 500 includes an n-type semiconductor region 504 and a p-type
semiconductor region 508. A reverse electric field is created at
the junction between the two regions, which cause the electrons and
holes to move away from the junction to form an active region 506.
When a forward voltage sufficient to overcome the reverse electric
field is applied across the p-n junction through a pair of
electrodes 510, 512, electrons and holes are forced into the active
region 506 and recombine. When electrons recombine with holes, they
fall to lower energy levels and release energy in the form of
light.
[0072] In this example, the n-type semiconductor region 504 is
formed on a substrate 502 and the p-type semiconductor region 508
is formed on the active layer 506, however, the regions may be
reversed. That is, the p-type semiconductor region 508 may be
formed on the substrate 502 and the n-type semiconductor region 504
may formed on the active layer 506. As those skilled in the art
will readily appreciate, the various concepts described throughout
this disclosure may be extended to any suitable layered structure.
Additional layers or regions (not shown) may also be included in
the LED 500, including but not limited to buffer, nucleation,
contact and current spreading layers or regions, as well as light
extraction layers.
[0073] The p-type semiconductor region 508 is exposed at the top
surface, and therefore, the p-type electrode 512 may be readily
formed thereon. However, the n-type semiconductor region 504 is
buried beneath the p-type semiconductor layer 508 and the active
layer 506. Accordingly, to form the n-type electrode 510 on the
n-type semiconductor region 504, a cutout area or "mesa" is formed
by removing a portion of the active layer 506 and the p-type
semiconductor region 508 by means well known in the art to expose
the n-type semiconductor layer 504 there beneath. After this
portion is removed, the n-type electrode 510 may be formed.
[0074] FIG. 11 is a conceptual cross-sectional view illustrating an
example of an LED with a phosphor layer. In this example, a
phosphor layer 602 is formed on the top surface of the LED 500 by
means well known in the art. The phosphor layer 602 converts a
portion of the light emitted by the LED 500 to light having a
different spectrum. A white LED light source can be constructed by
using an LED that emits light in the blue region of the spectrum
and a phosphor that converts blue light to yellow light. A white
light source is well suited as a replacement lamp for conventional
luminaries; however, the invention may be practiced with other LED
and phosphor combinations to produce different color lights. The
phosphor layer 602 may include, by way of example, phosphor
particles suspended in a carrier or be constructed from a soluble
phosphor that is dissolved in the carrier.
[0075] In a configuration of LED luminaries, an LED array may be
used to provide increased luminance. FIG. 12A is a conceptual top
view illustrating an example of an LED array, and FIG. 12B is a
conceptual cross-sectional view of the LED array of FIG. 12A. In
this example, a number of phosphor-coated LEDs 600 may be formed on
a substrate 702. The bond wires (not shown) extending from the LEDs
600 may be connected to traces (not shown) on the surface of the
substrate 702, which connect the LEDs 600 in a parallel and/or
series fashion. In some embodiments, the LEDs 600 may be connected
in parallel streams of series LEDs with a current limiting resistor
(not shown) in each stream. The substrate 702 may be any suitable
material that can provide support to the LEDs 600 and can be
mounted within a light fixture (not shown).
[0076] FIG. 13A is a conceptual top view illustrating an example of
an alternative configuration of an LED array, and FIG. 13B is a
conceptual cross-sectional view of the LED array of FIG. 13A. In a
manner similar to that described in connection with FIGS. 12A and
12B, a substrate 702 designed for mounting in a light fixture (not
shown) may be used to support an array of LEDs 500. However, in
this configuration, a phosphor layer is not formed on each
individual LED. Instead, phosphor 806 is deposited within a cavity
802 bounded by an annular ring 804 that extends circumferentially
around the outer surface of the substrate 702. The annular ring 804
may be formed by boring a cylindrical hole in a material that forms
the substrate 702. Alternatively, the substrate 702 and the annular
ring 804 may be formed with a suitable mold, or the annular ring
804 may be formed separately from the substrate 702 and attached to
the substrate using an adhesive or other suitable means. In the
latter configuration, the annular ring 804 is generally attached to
the substrate 702 before the LEDs 500, however, in some
configurations, the LEDs may be attached first. Once the LEDs 500
and the annular ring 804 are attached to the substrate 702, a
suspension of phosphor particles in a carrier may be introduced
into the cavity 802. The carrier material may be an epoxy or
silicone; however, carriers based on other materials may also be
used. The carrier material may be cured to produce a solid material
in which the phosphor particles are immobilized.
[0077] FIG. 14 shows exemplary devices including LEDs or LED
devices using metal traces in accordance with aspects of the
present invention. The devices 900 include a lamp 902, an
illumination device 904, and a street light 906. Each of the
devices shown in FIG. 14 includes at least an LED or an LED device
using metal traces as described herein. For example, lamp 902
includes a package 916 and an LED 908, in which LED 908 employs one
or more metal traces to provide flexible connections. Lamp 902 may
be used for any type of general illumination. For example, lamp 902
may be used in an automobile headlamp, street light, overhead
light, or in any other general illumination application.
Illumination device 904 includes a power source 910 that is
electrically coupled to a lamp 912, which may be configured as lamp
902. In an aspect, power source 910 may be batteries or any other
suitable type of power source, such as a solar cell. Street light
906 includes a power source connected to a lamp 914, which may be
configured as lamp 902. It should be noted that aspects of the LED
described herein are suitable for use with virtually any type of
LED assembly, which in turn may be used in any type of illumination
device and are not limited to the devices shown in FIG. 14.
[0078] The various aspects of this disclosure are provided to
enable one of ordinary skill in the art to practice the present
invention. Various modifications to aspects presented throughout
this disclosure will be readily apparent to those skilled in the
art, and the concepts disclosed herein may be extended to other LED
lamp configurations regardless of the shape or diameter of the
glass enclosure and the base and the arrangement of electrical
contacts on the lamp. Thus, the claims are not intended to be
limited to the various aspects of this disclosure, but are to be
accorded the full scope consistent with the language of the claims.
All structural and functional equivalents to the elements of the
various aspects described throughout this disclosure that are known
or later come to be known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. No claim element is
to be construed under the provisions of 35 U.S.C. .sctn.112, sixth
paragraph, unless the element is expressly recited using the phrase
"means for" or, in the case of a method claim, the element is
recited using the phrase "step for."
* * * * *